From: Andrea Righi Date: Tue, 31 Mar 2009 22:25:18 +0000 (-0700) Subject: fbmem: fix fb_info->lock and mm->mmap_sem circular locking dependency X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=66c1ca019078220dc1bf968f2bb18421100ef147;p=openwrt%2Fstaging%2Fblogic.git fbmem: fix fb_info->lock and mm->mmap_sem circular locking dependency Fix a circular locking dependency in the frame buffer console driver pushing down the mutex fb_info->lock. Circular locking dependecies occur calling the blocking fb_notifier_call_chain() with fb_info->lock held. Notifier callbacks can try to acquire mm->mmap_sem, while fb_mmap() acquires the locks in the reverse order mm->mmap_sem => fb_info->lock. Tested-by: Andrey Borzenkov Signed-off-by: Andrea Righi Cc: Geert Uytterhoeven Cc: Krzysztof Helt Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index 157057c79ca3..dd37cbcaf8ce 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -35,6 +35,8 @@ static int fb_notifier_callback(struct notifier_block *self, return 0; bd = container_of(self, struct backlight_device, fb_notif); + if (!lock_fb_info(evdata->info)) + return -ENODEV; mutex_lock(&bd->ops_lock); if (bd->ops) if (!bd->ops->check_fb || @@ -47,6 +49,7 @@ static int fb_notifier_callback(struct notifier_block *self, backlight_update_status(bd); } mutex_unlock(&bd->ops_lock); + unlock_fb_info(evdata->info); return 0; } diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c index b6449470106c..0bb13df0fa89 100644 --- a/drivers/video/backlight/lcd.c +++ b/drivers/video/backlight/lcd.c @@ -40,6 +40,8 @@ static int fb_notifier_callback(struct notifier_block *self, if (!ld->ops) return 0; + if (!lock_fb_info(evdata->info)) + return -ENODEV; mutex_lock(&ld->ops_lock); if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) { if (event == FB_EVENT_BLANK) { @@ -51,6 +53,7 @@ static int fb_notifier_callback(struct notifier_block *self, } } mutex_unlock(&ld->ops_lock); + unlock_fb_info(evdata->info); return 0; } diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index 1657b9608b04..2cd500a304f2 100644 --- a/drivers/video/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -2954,8 +2954,11 @@ static int fbcon_fb_unbind(int idx) static int fbcon_fb_unregistered(struct fb_info *info) { - int i, idx = info->node; + int i, idx; + if (!lock_fb_info(info)) + return -ENODEV; + idx = info->node; for (i = first_fb_vc; i <= last_fb_vc; i++) { if (con2fb_map[i] == idx) con2fb_map[i] = -1; @@ -2979,13 +2982,14 @@ static int fbcon_fb_unregistered(struct fb_info *info) } } - if (!num_registered_fb) - unregister_con_driver(&fb_con); - - if (primary_device == idx) primary_device = -1; + unlock_fb_info(info); + + if (!num_registered_fb) + unregister_con_driver(&fb_con); + return 0; } @@ -3021,9 +3025,13 @@ static inline void fbcon_select_primary(struct fb_info *info) static int fbcon_fb_registered(struct fb_info *info) { - int ret = 0, i, idx = info->node; + int ret = 0, i, idx; + if (!lock_fb_info(info)) + return -ENODEV; + idx = info->node; fbcon_select_primary(info); + unlock_fb_info(info); if (info_idx == -1) { for (i = first_fb_vc; i <= last_fb_vc; i++) { @@ -3124,7 +3132,7 @@ static void fbcon_get_requirement(struct fb_info *info, } } -static int fbcon_event_notify(struct notifier_block *self, +static int fbcon_event_notify(struct notifier_block *self, unsigned long action, void *data) { struct fb_event *event = data; @@ -3132,7 +3140,7 @@ static int fbcon_event_notify(struct notifier_block *self, struct fb_videomode *mode; struct fb_con2fbmap *con2fb; struct fb_blit_caps *caps; - int ret = 0; + int idx, ret = 0; /* * ignore all events except driver registration and deregistration @@ -3144,23 +3152,54 @@ static int fbcon_event_notify(struct notifier_block *self, switch(action) { case FB_EVENT_SUSPEND: + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } fbcon_suspended(info); + unlock_fb_info(info); break; case FB_EVENT_RESUME: + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } fbcon_resumed(info); + unlock_fb_info(info); break; case FB_EVENT_MODE_CHANGE: + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } fbcon_modechanged(info); + unlock_fb_info(info); break; case FB_EVENT_MODE_CHANGE_ALL: + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } fbcon_set_all_vcs(info); + unlock_fb_info(info); break; case FB_EVENT_MODE_DELETE: mode = event->data; + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } ret = fbcon_mode_deleted(info, mode); + unlock_fb_info(info); break; case FB_EVENT_FB_UNBIND: - ret = fbcon_fb_unbind(info->node); + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } + idx = info->node; + unlock_fb_info(info); + ret = fbcon_fb_unbind(idx); break; case FB_EVENT_FB_REGISTERED: ret = fbcon_fb_registered(info); @@ -3178,17 +3217,31 @@ static int fbcon_event_notify(struct notifier_block *self, con2fb->framebuffer = con2fb_map[con2fb->console - 1]; break; case FB_EVENT_BLANK: + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } fbcon_fb_blanked(info, *(int *)event->data); + unlock_fb_info(info); break; case FB_EVENT_NEW_MODELIST: + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } fbcon_new_modelist(info); + unlock_fb_info(info); break; case FB_EVENT_GET_REQ: caps = event->data; + if (!lock_fb_info(info)) { + ret = -ENODEV; + goto done; + } fbcon_get_requirement(info, caps); + unlock_fb_info(info); break; } - done: return ret; } diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index cfd9dce1ce0b..b64f061dd447 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -1086,13 +1086,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, return -EINVAL; con2fb.framebuffer = -1; event.data = &con2fb; - - if (!lock_fb_info(info)) - return -ENODEV; event.info = info; fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event); - unlock_fb_info(info); - ret = copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : 0; break; case FBIOPUT_CON2FBMAP: @@ -1109,12 +1104,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, break; } event.data = &con2fb; - if (!lock_fb_info(info)) - return -ENODEV; event.info = info; - ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, - &event); - unlock_fb_info(info); + ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event); break; case FBIOBLANK: if (!lock_fb_info(info))